The mounting of the stack of stator laminations in the machine housing or in the stator frame, respectively, must be designed in such a manner that it can withstand all radial and tangential forces occurring during operation, and especially in the case of a short circuit, without having to use elaborate machining and/or assembly techniques.
From DE-B2 No. 2,042,561, a turbo-generator having a laminated stack is known in which the laminated stack is suspended on its outside by means of dovetail-shaped wedges extending in its longitudinal direction in a housing, the dovetail-shaped wedges being joined via screw bolts to a wedge carrier which extends parallel to them and is fixed at the housing.
The wedge carriers partially engage recesses at the outside of the stack of stator laminations, resting without play against the recesses, and are designed to be tapered at the part engaging the inside of the stack of stator laminations. In this arrangement, the tapering of the wedge carriers is designed to be arc-shaped. The screw bolts are kept under constant tension by means of spring means supported on the wedge carriers. The wedge carriers are firmly joined to a stator frame arranged inside the housing.
This electric machine is produced in such a manner that first the stack of stator laminations is assembled and pressed together in the axial direction by means of compression plates arranged at its faces, after which the wedges are introduced into grooves provided on the outside of the stack of stator laminations and are clamped, by means of wedge carriers resting against contact faces provided on the outer surface of the stack of stator laminations, by means of the screw bolts. After that the stack of stator laminations clamped in such a manner by the wedges, wedge carriers, and compression plates is introduced into the stator frame and, after being centered with respect to the stator frame, the wedge carriers and the stator frame are firmly joined.
The known construction and arrangement of the wedge carriers ensures that the contact between housing and stack of stator laminations is free from play and is suitable for absorbing forces in the radial and circumferential directions. Simultaneously, the wedges and the screw bolts associated with them are completely relieved of circumferential forces. In addition, they can be retightened at any time.
In DE-B2 No. 2,042,561, the laminated stack is completed in its entirety outside the housing. After the wedges have been introduced and the wedge carriers have been clamped to the stack of stator laminations, the axially clamped stack of stator laminations is introduced into the stator frame and firmly joined to the latter. It is only after this that the stator frame and laminated stack are built into the housing.
In electric machines in which the laminated stack is laminated directly into the housing, the method of proceeding as described above cannot be applied in practice. The frictional connection between the housing and the laminated stack must be made only after the laminated stack has been compressed and consolidated, since otherwise the laminations would no longer be able to shift at the back of the laminated stack. In addition, all mounting points would have to be accessible from the outside over the entire iron length and over the entire circumference, and that in turn would necessitate a very large number of closable openings in the pressure-tight housing jacket.